View Types
Abstraction to build adapters with dynamic/variable view types count for Android application. It eliminates the need to manually define view types (via Enum<?>, or if you follow Google Developers advice integer constants (less memory usage, you know!)). Makes code readable and actually share view types across multiple screens (no need to write a new adapter, or add view types handling in one base adapter with endless switch statement).
Please note, RecyclerView only.
Installation
Add a dependency into your build.gradle:
compile `ru.noties:vt:1.0.0`
If you don't have RecyclerView dependency in your project already, you must add it also:
// at the time of writing the latest version is '25.0.0' // theoretically it should work with older versions as well, but I haven't tested it compile `com.android.support:recyclerview-v7:25.0.0`
Usage
final ViewTypesAdapter<One> adapter = ViewTypesAdapter.builder(One.class)
.register(One.class, new ViewTypeOne(), null) // will be not clickable
.register(Two.class, new ViewTypeTwo(), new OnItemClickListener<Two, HolderSingle<TextView>>() {
@Override
public void onItemClick(Two item, HolderSingle<TextView> holder) {
}
}
)
.register(Three.class, new ViewTypeOne())
.setHasStableIds(true) //
.registerOnDataSetChangedListener(new DiffUtilDataSetChanged<One>(true))
.registerOnDataSetChangedListener(new NotifyDataSetChanged<One>())
.registerOnClickListener(new OnItemClickListener<One, Holder>() {
@Override
public void onItemClick(One item, Holder holder) {
Debug.i("class: `%s`, value: %s", item.getClass().getSimpleName(), item.oneValue);
}
}
)
.build(this);
// context
ru.noties.vt.ViewType
The core class of this library is ru.noties.vt.ViewType<T, H extends Holder>
, where T
is the type of the item, and H
a subclass of ru.noties.vt.Holder
or ru.noties.vt.Holder
itself if you don't have RecyclerView.ViewHolder specific logic.
public abstract class ViewType<T, H extends Holder> {
protected abstract H createView(LayoutInflater inflater, ViewGroup parent);
protected abstract void bindView(Context context, H holder, T item, List<Object> payloads);
public long itemId(T item) {
return RecyclerView.NO_ID;
}
}
ru.noties.vt.Holder
public class Holder extends RecyclerView.ViewHolder {
public Holder(View itemView) {
super(itemView);
}
public <V extends View> V findView(@IdRes int id) {
//noinspection unchecked
return (V) itemView.findViewById(id);
}
}
Has one utility method to automatically cast view. For example:
final TextView text = findView(R.id.text);
There is also HolderSingle
if Holder holds exactly one view.
public class HolderSingle<V extends View> extends Holder {
public final V view;
public HolderSingle(View itemView) {
super(itemView);
//noinspection unchecked
view = (V) itemView;
}
public HolderSingle(View itemView, @IdRes int id) {
super(itemView);
view = findView(id);
}
}
For example:
// automatically cast whole view passed in constructor to TextView final HolderSingle<TextView> textHolder = new HolderSingle<>(itemView);
// automatically cast view found by id `R.id.image` to ImageView final HolderSingle<ImageView> imageHolder = new HolderSingle<>(itemView, R.id.image);
// textHolder.view -> TextView // imageHolder.view -> ImageView
ru.noties.vt.ViewTypesAdapter
Significant methods (without implementation):
public class ViewTypesAdapter<T> extends RecyclerView.Adapter<Holder> {
// [0]
public static <T> ViewTypesAdapter.Builder<T> builder(Class<T> base)
// [1]
public ViewTypes viewTypes()
// [2]
public <ITEM extends T> void setItems(@Nullable List<ITEM> items)
// [3]
public <ITEM extends T> void changeItems(List<ITEM> items)
// [4]
public List<T> getItems()
// [5]
public <ITEM extends T> ITEM getItem(int position)
// [6]
public <ITEM extends T> ITEM getItemAs(int position, Class<ITEM> itemClass)
}
- [0] - returns
ru.noties.vt.ViewTypesAdapter.Builder
to configure this instance of adapter. Adapter can be created via this builder only. - [1] - returns
ru.noties.vt.ViewTypes
generated by builder and which posses some important information about current view types (assigned view types, view types count) - [2] - starts process of updating items that this adapter displays (triggers notification)
- [3] - swaps items without notification must be used by
ru.noties.vt.OnDataSetChangedListener
only - [4] - returns items that this adapter has (can be null, if no items present)
- [5] - returns and automatically casts item at specified position
- [6] - returns item at specified position and casts it to the specified class parameter
ru.noties.vt.ViewTypesAdapter.Builder
This class contains all configuration that ViewTypesAdapter need
public static class Builder<T> {
// constructor
public Builder(Class<T> base)
// [0]
public <VIEW_TYPE_TYPE extends T, ACTUAL_TYPE extends VIEW_TYPE_TYPE, HOLDER extends Holder> Builder<T> register(
@NonNull Class<ACTUAL_TYPE> itemClass,
@NonNull ViewType<VIEW_TYPE_TYPE, HOLDER> viewType
)
// [1]
public <VIEW_TYPE_TYPE extends T, ACTUAL_TYPE extends VIEW_TYPE_TYPE, ON_CLICK_TYPE extends T, HOLDER extends Holder> Builder<T> register(
@NonNull Class<ACTUAL_TYPE> itemClass,
@NonNull ViewType<VIEW_TYPE_TYPE, HOLDER> viewType,
@Nullable OnItemClickListener<ON_CLICK_TYPE, HOLDER> click
)
// [2]
public <HOLDER extends Holder> Builder<T> registerOnClickListener(OnItemClickListener<T, HOLDER> click)
// [3]
public Builder<T> registerOnDataSetChangedListener(OnDataSetChangedListener<T> onDataSetChangedListener)
// [4]
public Builder<T> setHasStableIds(boolean hasStableIds)
// [5]
public ViewTypesAdapter<T> build(@NonNull Context context) throws ViewTypesException
}
- [0] - registers item with this adapter. The method signature is a bit monstrous, but it gives ability to share
ViewType
across multiple items. For example:register(String.class, ViewType<String, Holder>)
andregister<String.class, ViewType<CharSequence, Holder>)
are both valid. Please note that even some items can share the sameViewType
they will be treated as different view types (from adapter perspective) - [1] - Almost the same as [0], but also adds
OnItemClickListener
. There are two cases: if passed listener is NULL, then this item won't be clickable. If passed listener is NOT NULL then this listener will be triggered event if default listener (from [2]) is set - [2] - Registers default
OnItemClickListener
for all items registered via [0] method - [3] - registers
ru.noties.vt.OnDataSetChangedListener
for this adapter. If this method wasn't called (or called with NULL) the default value ofru.noties.vt.NotifyDataSetChanged
will be used - [4] - corresponds with
RecyclerView.Adapter.setHasStableIds
method. When set it's wise to override theViewType.itemId()
method - [5] - executes check for validity of data and returns ready-to-be-used
ViewTypesAdapter
. ThrowsViewTypesException
if this Builder instance was already built and if no items were registered via [0] or [1] methods
ru.noties.vt.OnDataSetChangedListener
This is class that evaluates the update logic of new items. It contains one method:
void onDataSetChanged(
ViewTypesAdapter adapter,
List<T> oldItems,
List<T> newItems );
There are 2 implementations of this interface that are bundled with this library: ru.noties.vt.NotifyDataSetChanged
and ru.noties.vt.DiffUtilDataSetChanged
. For example, ru.noties.vt.NotifyDataSetChanged
implementation is as follows:
@Override public void onDataSetChanged(ViewTypesAdapter adapter, List<T> oldItems, List<T> newItems) {
// please note that this listener must call `changeItems`, not `setItems`
adapter.changeItems(newItems);
adapter.notifyDataSetChanged();
}
ru.noties.vt.DiffUtilDataSetChanged
ru.noties.vt.DiffUtilDataSetChanged
is based on android.support.v7.util.DiffUtil
. It has 4 constructors:
// [0] public DiffUtilDataSetChanged() // [1] public DiffUtilDataSetChanged(boolean detectMoves) // [2] public DiffUtilDataSetChanged(ItemsChecker<T> itemsChecker) // [3] public DiffUtilDataSetChanged(ItemsChecker<T> itemsChecker, boolean detectMoves)
- [0] - is equvivalent of calling [3] with
new SimpleItemsChecker<>()
andfalse
- [1] - is equvivalent of calling [3] with
new SimpleItemsChecker<>()
anddetectMoves
- [2] - is equvivalent of calling [3] with
itemsChecker
andfalse
- [3] - constructor that accepts all possible configuration items
public static abstract class ItemsChecker<T> {
public abstract boolean areItemsTheSame(T oldItem, T newItem);
public abstract boolean areContentsTheSame(T oldItem, T newItem);
@Nullable
public Object getChangePayload(T oldItem, T newItem) {
return null;
}
}
public static class SimpleItemsChecker<T> extends ItemsChecker<T> {
@Override
public boolean areItemsTheSame(T oldItem, T newItem) {
return oldItem == newItem;
}
@Override
public boolean areContentsTheSame(T oldItem, T newItem) {
return (oldItem == null && newItem == null)
|| (oldItem != null && newItem != null && oldItem.equals(newItem));
}
}
ru.noties.vt.OnItemClickListener
public interface OnItemClickListener<T, H extends Holder> {
void onItemClick(T item, H holder);
}
ru.noties.vt.ViewTypes
Instance can be obtained via ViewTypesAdapter.viewTypes()
method.
// [0] public boolean supportsDataSet(List objects) // [1] public boolean supports(Class<?> first, Class<?>... others) // [2] public int viewTypeCount() // [3] public ViewType viewType(@NonNull Object item) throws ViewTypesException // [4] public ViewType viewType(int assignedViewType) throws ViewTypesException // [5] public int assignedViewType(@NonNull Object item) throws ViewTypesException // [6] public int assignedViewType(@NonNull Class<?> cl) throws ViewTypesException
- [0] - returns BOOLEAN showing that all items contain in the list have registered
ViewType
- [1] - returns BOOLEAN showing that all passed Classes have registered
ViewType
- [2] - returns total number of registered view types
- [3] - returns
ViewType
associated with provided item. ThrowsViewTypesException
is noViewType
is registered for this item - [4] - returns
ViewType
associated with providedassignedViewType
(returned by [5] or [6] method call). ThrowsViewTypesException
if noViewType
is associated withassignedViewType
- [5] - equvivalent of calling [6] with
item.getClass()
as a parameter - [6] - returns assigned view type for this Class. Throws
ViewTypesException
if class has no associated view type
License
Copyright 2016 Dimitry Ivanov ([email protected])
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.